[R] applying order() in a for loop

[Petr Pikal]

Hi

your code is strange and not reproducible. 
We do not have data
h is not defined but you use it in h <- rbind(h,z)

Based on what you say about your problem, I would probably try to 
split data frame into list accorging to "i". Then I would shufle 
columns in each part of list and then I would use lapply and do.call 
to concatenate all together


lll <- split(DF, i)
sss <- lapply(lll, function(x) order(colSums(x)))

# here could come for cycle 
xxx<-vector("list",3)
for (i in 1:3) xxx[i]<-list(as.matrix(lll[[i]][,sss[[i]]]))
do.call("rbind",xxx)

HTH
Petr




    

On 26 Oct 2006 at 15:40, Kim Milferstedt wrote:

Date sent:      	Thu, 26 Oct 2006 15:40:33 -0500
To:             	r-help at stat.math.ethz.ch
From:           	Kim Milferstedt <milferst at uiuc.edu>
Subject:        	[R] applying order() in a for loop

> Hi,
> 
> with the code below I try to organize sections of a data.frame. The
> dataframe has 9 data columns. I'd like to order the columns of the
> data.frame by the sum of the columns' entries. The sections of the
> columns are identified by "i". The order of the columns is given by
> the vector "z". Each section of the data.frame is ordered differently.
> This can be seen when looking at the individual rows of "h" where all
> different "z" vectors are stored for later use.
> 
> In a third for loop, "e" is calculated based on the ordering 
> calculated before. "e" is the re-organized data.frame with now all
> column segments in descending order -- in theory.
> 
> Problem:
> The code below does not update the "z" in the third for loop. It
> remains the initial "z" that I calculate the first time around. I
> tried re-initializing "z" at various places in the code, hoping to get
> rid of the old values but with no apparent consequences. Also in the
> help I could not find anything that I could relate to my problem.
> 
> Does anybody have a suggestion on how to get the appropriate "z" to
> work when shuffling the data around for "e"?
> 
> Thanks already for suggestions!
> 
> Kim
> 
> ### Code ####
> 
> for (i in 11:19)
>      {
>          for (j in 3:ncol(data))
>              {
>                  a <- sum(data[,j][data[,1] == i/10])
>                  b <- c(b,a)
>              }
> 
>          z <- order(b, decreasing = TRUE)
>          d <- length(data[,1][data[,1] == i/10])
> 
>          h <- rbind(h,z) ### Just to check whether I really get 
> different orderings for the different data segments.
> 
>          for (l in 1:d)
>              {
>                  e <- data[((i-10)*d+l-d),(3:ncol(data))][z] ## This z
> does not get updated but remains the initially calculated z
>                  f <- rbind(f,e)
>              }
>          b <- NULL
>          e <- NULL
>          z <- NULL
>      }
> 
> ______________________________________________
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> PLEASE do read the posting guide
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> minimal, self-contained, reproducible code.

Petr Pikal
petr.pikal at precheza.cz